JP5467738B2 - Rubber composition and tire using the same - Google Patents

Description

  The present invention relates to a rubber composition and a tire using the same, and more particularly to a rubber composition that can be used in a tire and expected to reduce fuel consumption of an automobile or the like equipped with the tire, and a tire using the rubber composition. is there.

As interest in the environment and safety increases, there is a strong demand for improved fuel efficiency and improved wear resistance by reducing rolling resistance on tires.
By the way, a tire in which carbon black having characteristics such as a CTAB specific surface area of 110 to 170 m ² / g and a 24M4DBP compression oil absorption of 100 to 130 ml / 100 g is blended with a diene rubber in order to improve the wear resistance of the tire. A rubber composition has been proposed (see, for example, Patent Document 1). Further, by reducing the CTAB specific surface area, that is, by increasing the primary particles of carbon black, the distance between primary particles of carbon black in the rubber is increased, and the friction between primary particles due to rubber deformation is reduced. It is also considered to reduce rolling resistance by suppressing heat generation.
Japanese Patent Laid-Open No. 5-230290

  By the way, if the CTAB specific surface area is small, there is a problem that the contact area with the polymer becomes small, and sufficient reinforcement with carbon black cannot be obtained, resulting in a decrease in wear resistance. Therefore, it is desired to add carbon black having characteristics capable of exhibiting high wear resistance and low rolling resistance of the tire to the rubber composition.

  In order to solve the above-mentioned problems, the present invention provides a fuel during running of an automobile equipped with the wear resistance, the tire life, and the rolling resistance when the tire tread rubber is used. An object of the present invention is to provide a rubber composition and a tire using the same, which can reduce the consumption of the rubber.

As a result of intensive studies to solve the above problems, the present inventor has repeatedly studied the characteristics of carbon black from a viewpoint different from the conventional one, and has the same CTAB specific surface area, that is, the same primary particle diameter. , By measuring the mercury intrusion of the specific surface area by mercury porosimetry, and using the one with a larger mercury intrusion specific surface area than the conventional one, it was found that the reinforcing property of the rubber was improved and the present invention was completed. It was.
Mercury does not press into the smallest micropore of 6 nm among the pores of carbon black. The rubber component is pressed into relatively large pores larger than mesopores that can be easily adsorbed. This represents the specific surface area of the carbon black surface having a size larger than the mesopores. When this value is large, the contact area with the rubber component is increased even if the CTAB specific surface area is equal. It can be expected that heat generation due to rubbing of the primary particles can be suppressed and the reinforcement can be enhanced.

That is, the rubber composition of the present invention has a mercury intrusion specific surface area X measured by mercury porosimetry on at least one rubber component selected from the group consisting of natural rubber, synthetic isoprene rubber, and synthetic diene rubber. Carbon black in which (m ² / g) and CTAB specific surface area Y (m ² / g) satisfy the relationship of X / Y ≧ 0.84 is blended. The blending amount is preferably in the range of 10 to 100 parts by mass with respect to 100 parts by mass of the rubber component.
The carbon black preferably has a CTBA specific surface area Y (m ² / g) of 80 ≦ Y ≦ 160 and a 24M4DBP compression oil absorption Z (ml / 100 g) of 80 <Z <130.

  The tire of the present invention is characterized by using the rubber composition in a tread.

Conventional carbon black aggregates primary particles to form a structure, but the structure has many fine pores that do not allow polymer to enter. The rubber composition of the present invention uses carbon black having a structure in which the number of pores through which polymer cannot enter is reduced by production different from conventional carbon black. That is, instead of the conventional carbon black in which the ratio X / Y of the mercury intrusion specific surface area X and the CTAB specific surface area Y is less than 0.84, the carbon black in which the X / Y relation satisfies 0.84 or more. And carbon black having pores effective for polymer adsorption. As a result, the wear resistance of the tire used for the tread rubber can be remarkably enhanced without deteriorating the rolling resistance, and the amount of fuel consumed while the automobile equipped with the tire is running can be reduced. The carbon black preferably has a CTBA specific surface area Y (m ² / g) of 80 ≦ Y ≦ 160 and a 24M4DBP compression oil absorption Z (ml / 100 g) of 80 <Z <130. When the CTAB specific surface area is less than 80 m ² / g, the wear resistance is lowered, and when it exceeds 160 m ² / g, the dispersibility of carbon black in the rubber component is lowered and the processability is deteriorated. When the tread rubber is used, the low rolling resistance of the tire is deteriorated. Further, when the 24M4DBP compression oil absorption Z is 80 ml / 100 g or less, the wear resistance is lowered, and when it is 130 ml / 100 g or more, the unvulcanized degree of the rubber composition is remarkably increased and the workability is deteriorated.

Hereinafter, preferred embodiments of the present invention will be described in detail.
The rubber component of the rubber composition of the present invention is at least one rubber selected from the group consisting of natural rubber, synthetic isoprene rubber and synthetic diene rubber. Examples of the diene-based synthetic rubber include styrene-butadiene copolymer (SBR), polybutadiene (BR), polyisoprene (IR), butadiene-isoprene copolymer, butadiene-styrene-isoprene copolymer, and acrylonitrile-butadiene. Copolymers, chloroprene rubber, butyl rubber, halogenated butyl rubber and the like can be mentioned. These rubbers and natural rubbers may be used alone or in combination of two or more.

The characteristics of the carbon black used in the present invention are such that the mercury intrusion specific surface area X (m ² / g) and the CTAB specific surface area Y (m ² / g) measured by mercury porosimetry are X / Y ≧ 0.84. Satisfy the relationship.
Preferably, the CTBA specific surface area Y (m ² / g) is 80 ≦ Y ≦ 160, and the 24M4DBP compressed oil absorption Z (ml / 100 g) is 80 <Z <130.
The mercury intrusion specific surface area X was measured using a mercury porosimeter 2000 type manufactured by QUANTACHROME (distributor: Yuasa Ionics Co., Ltd.). In this apparatus, the contact angle θ = 140 ° and the mercury surface tension σ = 480 dyne / cm are employed in the Washburn relational expression. Since pressurization is performed up to 30000 vapor pressure (PSIA), the pore measurement range has a pore diameter of about 6 nm or more.
CTAB specific surface area Y is an abbreviation for cetyltrimethylammonium bromide adsorption specific surface area, and the above values are values measured in accordance with IASTM D3765-80. The 24M4DBP compression oil absorption Z is an abbreviation for dibutyl phthalate oil absorption, and is a value measured in accordance with ASTM D3493-85a.

  Examples of carbon black include channel black, furnace black, acetylene black, and thermal black depending on the production method. The blending amount of the carbon black is preferably 10 to 100 parts by weight, particularly preferably 20 to 80 parts by weight with respect to 100 parts by weight of the rubber component. When the content is within the range, the wear resistance exhibits a sufficient value, and the desired performance can be sufficiently obtained.

In the present invention, carbon black does not press fit into pores smaller than the smallest micropore 6 nm. For this reason, carbon black has relatively large pores equal to or larger than mesopores capable of easily adsorbing rubber components having a small pore radius of less than 50 mm. Therefore, the mercury intrusion specific surface area X of the carbon black of the present invention is preferably as close as possible to the CTAB specific surface property Y, and X / Y is at least 0.84 or more as described above, and preferably 0.8. 85 or more.
In this case, the initial blending with natural rubber and diene synthetic rubber is good, and even if the CTAB specific surface area is equal, the contact area with the rubber component can be increased, and the primary particles are rubbed together. Heat generation is suppressed and rubber reinforcement is enhanced.

In addition, examples of preferable powder properties include the following values. However, it goes without saying that the present invention is not limited to these numerical ranges.
The CTAB specific surface area Y (m ² / g) is preferably 80 ≦ Y ≦ 160, and more preferably 90 ≦ Y ≦ 150. Within this range, the dispersibility in the rubber component is good and the processability is good, and the abrasion resistance and low rolling resistance as a tire can be sufficiently achieved. When the CTAB specific surface area is less than 80 m ² / g, the wear resistance is lowered, and when it exceeds 160 m ² / g, the dispersibility of carbon black in the rubber component is lowered and the processability is deteriorated. When the tread rubber is used, the low rolling resistance of the tire is deteriorated.
The 24M4DBP compressed oil absorption amount Z (ml / 100 g) is preferably 80 <Z <130, and more preferably 90 ≦ Z ≦ 120. Within this range, wear resistance is reduced at 80 ml / 100 g or less, and the unvulcanized viscosity of the rubber composition is remarkably increased at 130 ml / 100 g or more, resulting in poor processability.

  The rubber composition of the present invention includes, in addition to the carbon black, a compounding agent usually used in industry, such as a reinforcing filler, a vulcanizing agent, a vulcanization accelerator, a vulcanization acceleration aid, a softening agent, An anti-aging agent or the like can be appropriately blended, and the rubber composition can be obtained by kneading using a closed kneader such as a Banbury mixer or an intermixer or a kneader such as a roll.

  The tire of the present invention is characterized in that the rubber composition of the present invention is used for a tread. The material other than the tread and the tire structure are not particularly limited, and can be appropriately selected. In the tire of the present invention, not only air but also nitrogen and other inert gases can be filled.

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to the following examples.
Test rubber compositions in Examples and Comparative Examples shown in Tables 3 and 4 described below were prepared by kneading based on the formulation shown in Table 1 below.
Moreover, about the carbon black of each Example, the carbon black obtained by the manufacturing method on the conditions of the following Table 2 or the commercially available carbon black was used.

<Method for producing carbon black>
The carbon black production apparatus consists of a substantially cylindrical furnace. A fuel inlet and an air inlet are provided at the upstream end of the furnace. In the upstream portion of the furnace, a combustion gas generation chamber is formed in which fuel gas and air gas (oxygen-containing gas) are mixed to generate a high-temperature combustion gas flow. The combustion gas generation chamber has a length of 1000 mm and an inner diameter of 595 mmφ. An intermediate transition chamber (including a raw material introduction chamber) having an inner diameter gradually reduced is provided downstream of the combustion gas generation chamber. The length of the intermediate transition chamber is 1700 mm, and the diameter of the narrowest flange portion on the most downstream side is 70 to 300 mm. Further, an installation hole (introduction position) for the raw material introduction nozzle is formed on the side wall at a position of 100 mm and 200 mm from the narrowest flange portion at the most downstream side of the intermediate transition chamber to the upstream side. Eight installation holes are formed in the peripheral wall of the furnace, and a raw material nozzle is installed in each hole according to the implementation conditions. Moreover, the inner diameter shape of the cross section of the furnace at the position where the raw material nozzle is installed is circular or substantially elliptical. In the case of an elliptical shape, the longest diameter (longest distance) / shortest diameter (shortest distance) is the manufacturing condition.
A carbon black generation chamber is provided downstream of the intermediate transition chamber, and a cooling medium introduction port for stopping the reaction is provided in the generation chamber at a position of 2000 mm and 3000 mm from the narrowest portion. The quenching position is determined by providing the cooling medium introducing means at the inlet.
Using the carbon black production apparatus, carbon black a to j were produced under the conditions shown in Table 2 below using heavy oil as a raw material and A heavy oil as a fuel.

<Commercially available carbon black>
* Carbon black N330 (VULCAN3 manufactured by Cabot)
* Carbon black N234 (VULCAN7H manufactured by Cabot)
* Carbon black N134 (Cabot VULCAN10H)

In addition, using the various rubber compositions obtained as tread rubbers, truck tires of size 11R22.5 were produced according to a conventional method, and the rolling resistance and abrasion resistance of the tires were evaluated by the following methods.
(1) Rolling resistance The above-mentioned truck tire was rotated freely on a drum, the rolling resistance was measured, and the rolling resistance value of the tire of Comparative Example 3 was indicated as 100, and displayed as an index. The smaller the index, the smaller the rolling resistance and the better.
(2) Abrasion resistance The tire was mounted on a vehicle, and the amount of decrease in the groove of the tire at the time of traveling 40,000 km was measured. It shows that it is excellent in abrasion resistance, so that an index | exponent is large.
The above results are also shown in Tables 3 and 4.

From Table 3 and Table 4 above, Reference Example 1 has improved wear resistance (91) while maintaining low rolling resistance (87) as compared to Comparative Example 4. In Reference Example 2, the rolling resistance is improved while maintaining the wear resistance. In Example 1-3 , the rolling resistance is slightly inferior, but the wear resistance is remarkably improved.

  The rubber composition of the present invention is obtained by blending a specific carbon black with a rubber component. When such a rubber composition is used in a tire tread, the wear resistance is high, the tire life is long, and the rolling resistance is high. This is an industrial applicability that can reduce the fuel consumption while driving a car equipped with it.

Claims (3)

A rubber component comprising at least one selected from the group consisting of natural rubber, synthetic isoprene rubber, and synthetic diene rubber,
A mercury intrusion ratio is measured by mercury porosimetry surface area X ^(m 2 / g) and a CTAB specific surface area Y ^(m 2 / g) is satisfied a relationship of X / Y ≧ 0.84, the CTAB specific surface area Y ( m ² / g) is 80 ≦ Y ≦ 160, and 24M4DBP compression oil absorption Z (ml / 100 g) is 80 <Z ≦ 108, and a rubber composition characterized by containing carbon black.   The rubber composition according to claim 1, wherein the carbon black is blended in an amount of 10 to 100 parts by mass with respect to 100 parts by mass of the rubber component. A tire comprising the rubber composition according to claim 1 or 2 as a tread.